The message of self-improvement and the idea that there is no ceiling to limit a person's accumulation of wealth are both directed at the middle class. This concept is generally aligned closely with the American Dream, a middle class dream wherein people leap from one economic class to another.
Epollock makes an excellent point. Theme is indeed a universal truth about life, human nature, relationships, and etc. that the author tries to convey through the writing. So what is Miller trying to say about the dreams of the American middle class?
One particular way the theme of middle class is applicable to Miller's work is the preoccupation with money. One element which is present in Wily's thought process is how money would solve all of his problems. Wily genuinely believes that success and money are compatible, and that the quantification given in the latter is present in the calculations of the former. There is a perpetual uneasiness in Wily's conception of himself, and this might be analgous to the middle class' perception of money. While they are not poor or impoverished and are not wealthy, the uneasiness caused by this lack of classification is evident in Wily and his dreams. In the final analysis, Miller conceives of Wily as a majority of Americans, most of whom are middle class who are besieged with a series of conditions that make their lives difficult, challenging, and one devoid of any easy answers.
There are many ways in which the death of a salesman can resonate with the middle class or for that matter any person. The reason for this is because the work deals with two things in particular. First, it deals with the idea of hard work. We Americans believe that hard work will be rewarding and create meaning in life, but when we buy into this like Willy Loman, we will begin to ask,"now what" or "is this it." I think many people are asking this now in view of the economy. The second theme is the haunting idea of death, the great leveler of all things. In short, we have only amount of time of earth. What will we do with it? Only work?
Even though Willy Loman's name suggests otherwise, he does largely reflect the American middle class of the play's setting. For most, the middle class should symbolize the essence of the American Dream--it is normally made up of people who are hard working and who believe that if they continue working hard or bettering their education, then America will allow them to fulfill their personal goals. In the play, Willy has become disillusioned with the American Dream as many middle class members did during the Modern American time period. He sees himself as someone who has worked diligently his whole life with nothing to show for it. His sons do not respect him; his wife does not fulfill him, and his job no longer requires him. He, like others from the middle class, focuses on the tangible evidence of success in life rather than on the intangible (relationships, personal growth, etc.). In the end, it's not enough for the middle class salesman to be stuck in the middle class.
I think you mean the subject of middle class. A subject is a concrete or abstract concept that the work demonstrates. A theme, on the other hand, is a universal truth that the work reveals expressed as a sentence. It is always harder to come up with a theme rather than than merely identify concepts in a work.
In America the middle class ideology is to own one's own home, a single family dwelling, owning a car, having children, and working at the same job until retirement. While some things have changed through the years, the concept that was present during the year Arthur Miller wrote the play "Death of a Salesman" has not changed that much. Taking a look at America's present day economy one can still identify people who share the same struggles and dreams with Willie Lowman.
The sales industry has also taken a nose dive in some areas of products. The results have been increased layoffs and depression for employees unable to meet heir mortgages. Willie was facing a reduction in his own ability to produce the quota of work necessary for his family's survival. He was watching his dream slip away. Many people are currently faced with the same situation which supports your theme.